Pulsating white dwarfs

Gravitational Radiation from Pulsating White Dwarfs

Rotating white dwarfs undergoing quasi-radial oscillations can emit gravitational radiation in a frequency range from 0.1 − 0.3 Hz. Assuming that the energy source for the gravitational radiation comes from the oblateness of the white dwarf induced by the rotation, the strain amplitude is found to be ∼ 10 for a white dwarf at ∼ 50 pc. The galactic population of these sources is estimated to be ...

Seismology of pre-white dwarfs: Models for pulsating sdB stars

Two kinds of pre-white dwarf stars can be probed through asteroseismology: planetary nebula nuclei (PNNs) and sdB (EHB) stars. To exploit the observed pulsations requires models that incorporate state-ofthe-art input physics and realistic evolutionary histories. Pulsation analysis of extensive grids of such models provide self-consistent theoretical pulsation periods for comparison with observe...

Mode identification of Pulsating White Dwarfs using the HST 1

Pulsating young brown dwarfs

We present the results of a nonadiabatic, linear stability analysis of models of very low-mass stars (VLMSs) and brown dwarfs (BDs) during the deuterium burning phase in the center. We find unstable fundamental modes with periods varying between ∼5 hr for a 0.1 M⊙ star and ∼1 hr for a 0.02 M⊙ BD. The growth time of the instability decreases with decreasing mass and remains well below the deuter...

Might Carbon - Atmosphere White Dwarfs Harbour a New Type of Pulsating Star ?

Aims. In the light of the recent and unexpected discovery of a brand new type of white dwarfs, those with carbon-dominated atmospheres, we examine the asteroseismological potential of such stars. The motivation behind this is based on the observation that past models of carbon-atmosphere white dwarfs have partially ionized outer layers that bear strong resemblance with those responsible for mod...